The new element "Leo (L)" has three stable isotopes: L-82 (exact mass: 81.8735), L-85 (exact mass: 84.8322), and L-86 (exact mass: 85.6299). The relative abundances are 64.8%, 18.5%, and 16.7%, respectively. What is the average atomic
mass of element L?

Which of the following is a compound? a. carbon b. oxygen c. hydrogen d. water

11. phosphorus-32 is radioactive and has a half life of 14 days. how much of a 124 mg sample of phosphorus-32 is present after 56 days? a) 7.75 mg b) 15.5 mg c) 31.0 mg d) 62.0 mg

Why is the bond angle in a water molecule less than the bond angle of methane? a. the central oxygen atom in water has two lone pairs of electrons, whereas the central carbon atom in methane has no lone pairs. b. the central hydrogen atom in water has one lone pair of electrons, whereas the central carbon atom in methane has two lone pairs. c. the central oxygen atom in water has four lone pairs of electrons, whereas the central carbon atom in methane has only one lone pair. d. the central oxygen atom exerts more repulsive force on surrounding atoms than the central carbon atom in methane does. reset next